Field of the Invention
The invention relates in general to light emitting device, and more particularly to a light emitting device with excellent heat dissipation efficacy.
Description of the Related Art
Currently, light emitting device, such as a light emitting diode (LED) lamp, has replaced the traditional fluorescent bulb lamp for some advantages such as higher lifespan, lower power consumption and smaller size. A LED lamp requires a light housing for fixing and protecting the LEDs. The heat dissipating efficacy of the light housing is important since the LEDs can be damaged by the thermal generating from the LEDs. Typically, a heat spreader is disposed on the heat dissipating side of the light housing for promoting the heat dissipating efficacy of the light housing.
In one type of the conventional LED lamp on street, heat spreader is exposed to the outside. This exposed heat spreader increases the surface area of the heat dissipating surface on the housing of the LED lamp, and remains the light emitting surface of the LED lamp at relatively low temperature when the high power LEDs on the light emitting surface of the LED lamp are working. However, the dust and sand are easily deposited on the gap of the exposed heat spreader.
However, heat dissipating efficacy of the light housing is unsatisfactory for the market requirements, since a large amount of the heat-insulating air surrounding the heat spreader are also enclosed in the light housing.